Geology And Geophysics

A Guide to Backyard Geology



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My love for all kinds of stones started right at birth! My parents named me Petra, a name derived from the Greek word (petros) rock and the name fits me to a T! I was genuinely fascinated with river rocks I found in my backyard or at the lake when my parents and I went fishing.

When I was about 10 years old I received my first kids' science book for Christmas. It was a book about geology and explained in easy-to-understand, child-friendly language the makings of our planet, from the shifting of the continental plates to volcanoes, as well as the mining of goods like charcoal and iron ore. My favorite thing in the world, however, as I mentioned earlier, have always been gemstones, minerals, precious metals and fossils - and this book explained in detail on how to find all of those geologic treasures! It also taught me how to tell certain types of gemstones from others, how to use different methods to compare the hardness and the color of minerals in your ever-growing rock collection and much more. Over the years I made friends with people with similar interests like my Dad's colleague Dieter who himself is an amateur geologist. He took my Dad and me on a few field trips that once involved colorful quartz deposits and at other times would lead us to a rock collector's flea market. I loved it - I just could not take my eyes off beautiful sliced agates and "thunder-egg" amethysts, shiny snowflake obsidian and fascinating bernstein -enclosed insects and plant leaves that lived millions of years ago!
I finally wanted to see for myself what my own backyard had to offer. Buying those magnificent witnesses of our planet's history simply isn't the same as digging them out of the dirt yourself!

I found that a lot of interesting geologic resources on your own backyard are available at schools, libraries and, of course, on the Internet. You may also want to check with your local "Geological Survey".

When occupying yourself with geology, though, one of the most important things is to keep your eyes open and study your surroundings. More often than not you'll notice geological features that will tell you whether you are on sedimentary ground that had been formed by an ancient body of water through accumulation of sand and calcium-rich shells etc, or if you are on metamorphic ground (influenced by volcanic pressure and heat), where you might encounter granite, or possibly even in a volcanic area, where you will often find lava rocks like basalt and tuff .

When I started researching my geological backdrop, I found that the area of my home country Germany that I lived in had a history of a hotter climate with a large growth of rain forests (which fostered the formation of different types of charcoal), and that parts of it had been underwater for a very long time, giving prehistoric sea creatures like trilobites and belemnites a chance to form a habitat before becoming extinct and vanishing in the depths of the ocean floor and time. I was going to work mostly with sedimentary ground here and I was to expect layers of sandstone, calcium, shells and diverse fossils, charcoal, lignite and a variety of gems you might find in an ocean, like bernstein , quartz etc! That seemed to be easy enough! But with the research comes a good bit of work!

You will definitely want to be dressed appropriately when going on a gem hunt. Ankle-high boots with a slip-resistant sole are a must; and you want to be dressed right for the season. Finally, consider, if you are going to look for rocks near a body of water or stream, or, if you might take a hike in the mountains.

Some essential tools to pack are a small pick, a hammer, a shovel (a small fold-up one works great most of the time) and a bottle of water to clean off your treasure to get a better look. When fossil hunting, you should also bring a fairly stiff bristle brush to gently clean crevices.
If you are more of a gold prospector, (as you might be if you live in the great Northwest of the U.S. like I do now) you really want to invest in a good gold pan with riffles and a sluice box. You will usually want to use a so-called "snuffer" bottle to collect gold flakes. Metal detectors can also a lot of fun when looking for precious metals.
I personally like using a sluice box in a stream, because of the fact that you often "catch" more than just gold. I have found many nice agates, garnets and copper while using my sluice box to separate gold from fiction, ahem - I mean black sand (magnetite)!

My point is - you can find a lot of pretty stuff in your own backyard, but if you specialize and only "hunt" for one type of geological treasure, be prepared to move a lot of dirt and sand! It's more fun to look for the unexpected - if you know what I mean!

One important rule to remember, when collecting rocks, is, that you should mark them (or include a note) with the date of your find, the exact location, depth and the type of stone you found. You also want to mention special features, approximate age based on prior research of the area, inclusions and the like. Even a sketch of the surroundings might be helpful as stream beds and other landscape features can change with yearly flooding, drought and wind erosion. Knowing what changed can often make your rock hunt more successful as new deposits of gold, for example, might be exposed.
Another thing to keep in mind, to avoid damage to your finds, is to be sure to wrap them up very well (newspaper is a good choice) and transport it in a sturdy box or bag.

Remember that when you find your gemstones in the raw, they are far from pretty most of the time. Their beauty usually only emerges after being cut into shape or being run through a rock tumbler. Some exceptions are geodes. They used to be gas bubbles within volcanic ash in which crystals formed. The ash settled and partially hardened around the gas bubbles. The geodes (some people refer to them as "thunder-eggs") are usually still soft when you find them, so you need to let them dry out for about a day or two before you break them open to discover the magnificent crystal structures inside.

Lastly, expect your rock-collection to grow huge over time, since there are millions of different types of rocks and minerals on this planet!
I recommend setting aside a small room or section of your home to display and store your proudest geological finds! But before you start - beware - this hobby is addictive!




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